Mixed gauge in strong laser-matter interaction

TL;DR

This paper introduces a mixed gauge approach for laser-matter interaction modeling, combining length and velocity gauges to improve accuracy and efficiency in simulating photoelectron spectra.

Contribution

It develops a practical mathematical and numerical framework for mixed gauge, demonstrating its advantages over traditional gauges in laser-matter interaction simulations.

Findings

Mixed gauge improves accuracy of photoelectron spectra calculations.

Mixed gauge offers rapid convergence and efficient absorption of outgoing flux.

Advantages over pure length or velocity gauges are demonstrated.

Abstract

We show that the description of laser-matter interaction in length gauge at short short and in velocity gauge at longer distances allows for compact physical modeling in terms of field free states, rapidly convergent numerical approximation, and efficient absorption of outgoing flux. The mathematical and numerical framework for using mixed gauge in practice is introduced. We calculate photoelectron spectra generated by a laser field at wavelengths of 400$\sim$800 nm from single-electron systems and from the helium atom and hydrogen molecule. We assess the accuracy of coupled channels calculations by comparison to full two-electron solutions of the time-dependent Schrodinger equation and find substantial advantages of mixed over velocity and length gauges.